Thanks ktm450. I have another question though to anybody who can help. I've now run diagnostics with the following displayed; "Middle loop #18", "Bar motor up #41",  "Not used #49". The death star  started operating by itself again last night though not always correctly as some times it should have been up and it was down. I assume this is the "Bar motor up" issue but not quite sure as my manual is incomplete.
 I should also note the drop targets don't register a score. Anyway, off to the shop now for some fuses and I'll go from there.
Cheers